Help!! I am trying to identify what these are. Have been to three jewelers no luck

[JimboinLq]

hello!! I am looking to identify this stone/shell. They are about thumb size but are very heavy like a stone.

 

[pearlsngems]

Some sort of dyed shell, I'd say.

 

[Bron357]

To me they look like they are man made from glass.

 

[stracci2000]

It looks like the polished thicker part of the mussel shell.
The mussel shell that is used for growing freshwater pearls is very lusterous and the pieces you have are the polished chunks from that shell. See diagram below. It looks just like your photo.